Spatial Distribution of Right Ventricular Perfusion Abnormalities Following Acute Right Coronary Artery Occlusion: A Study by Myocardial Contrast Echocardiography and Blue Dye Staining

Abstract

Although echocardiography is used for diagnosing right ventricular (RV) infarction produced by right coronary artery (RCA) occlusion, there has been no data on the spatial distribution of RV perfusion abnormalities following acute RCA occlusion. We examined this distribution by myocardial contrast echocardiography (MCE) and blue dye staining in canine models. The RCA was occluded in 10 open-chest dogs. MCE was performed with 0.27 g/min Levovist infusion by harmonic power Doppler with electrocardiogram gated intermittent triggered imaging at baseline and at 90 min after RCA occlusion. The opacification defects were assessed at the basal, middle, and apical levels of the RV free wall by short-axis view. The extent of the risk area of the occluded RCA, expressed as a percentage of the RV free wall, was measured at each level by injecting blue dye at the end of the experiments. In 10 other dogs, the left anterior descending coronary artery (LAD) was occluded by ligating the proximal portion of the LAD to examine the territory of the LAD on the same levels of the RV free wall by injecting blue dye. Although patchy opacification defects accompanying RV dilation were observed at the basal and middle levels during RCA occlusion, no apical defects were observed in any dogs by MCE. The risk area of the occluded RCA, as delineated by blue dye, was larger in the basal than apical level of the RV free wall in all 10 dogs (basal: 79 +/- 9%; middle: 48 +/- 14%; apical: 3 +/- 6%, p < 0.0001). The risk area of the occluded LAD (basal: 17 +/- 7%; middle: 12 +/- 6%; apical: 6 +/- 6%) was smaller than the risk area of the occluded RCA at the basal and middle levels of the RV free wall (p < 0.0001), and no significant difference was observed at the apical level. RV perfusion abnormalities produced by RCA occlusion are larger in the basal than apical level of the RV free wall. This finding elucidates the spatial distribution of the territory of the RCA on the RV free wall, and may help in identifying and assessing RV ischemia by echocardiography in humans. Moreover, the data in the current study indicate that RV infarction may be produced by occlusion of the coronary arteries except RCA, because the territory of the LAD on the RV free wall is clearly delineated.